Spontaneous combustion tendency of fresh and pre-oxidized sulfide ores简

Three representative sulfide ore samples were collected from typical metal mines,and their corresponding pre-oxidized products were obtained under nature environment.The thermal behaviors of each sample at heating rates of 5,10,15 and 20 °C/min in air flow from ambient temperature to 800 °C were studied by simultaneous thermal analysis and the TG/DSC curves before and after the pre-oxidation were compared.By the peak temperature of DTG curves,the whole reaction process for each sample was divided into different stages,and the apparent activation energies were calculated by the Ozawa-Flynn-Wall method.The results show that the reaction process of each sample after pre-oxidation is more complex,with quicker reaction rates,fewer heat production quantities,and higher or lower ignition-points.The apparent activation energies decrease from 364.017-474.228 kJ/mol to 244.523- 333.161 kJ/mol.Therefore,sulfide ores are more susceptible to spontaneous combustion after the pre-oxidation.     

FAULT TREE ANALYSIS OF SPONTANEOUS COMBUSTION OF SULPHIDE ORES AND ITS RISK ASSESSMENT

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Investigation of chemical suppressants for inactivation of sulfide ores

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Bioleaching of complex polymetallic sulfide ores by mixed culture

Bacterial leaching of single sulfide minerals and polymetallic sulfide ores was operated in shake flasks and small-scaled columns.The results show that bioleaching of jamesonite is not accessible,the iron extraction rate of pyrrhotite bioleaching reaches 98.2% after 26 d,and the zinc extraction rate of marmatite bioleaching reaches 92.3%,while the corresponding iron extraction reaches only 13.6% after 29 d.Pulp density has a significant effect on metal extraction of pyrrhotite and marmatite bioleaching.The corresponding metal extraction rate decreases with the increase of pulp density.For the polymetallic sulfide ores,zinc extraction of 97.1% is achieved after bioleaching in shake flasks for 10 d,while only 7.8% is obtained after bioleaching in small-scaled column.Analytical results of scanning electron microscopy（SEM） and energy dispersive X-ray analysis（EDX） reveal that large amount of calcium sulfate is formed on the mineral surface.     

Coupling of anionic wetting agents to dust of sulfide ores by dropping liquid method

By using the experimental approach of dropping liquid, the coupling of three anionic wetting agents with ten dust samples of sulfide ores was studied, and particularly the wetting effects of the wetting agents on the sulfide dust influenced by factors of agent concentration and sulfate additive in the wetting agent solutions were investigated. The results show that when the solution temperature is about 20℃, all the selected wetting agents are effective to most dust samples, but the effect is different. Wetting agents are more effective to the dust which is difficult to be wetted. Wetting agent solution with sodium sulfate can improve the wetting ability of sulfide dust. For sodium dodecyl benzene sulfonate, the suitable concentration of sodium sulfate is 1 - 2 mmol/L. The cost of wetting agents can be reduced because the sodium sulfate is much cheaper than many surfactants. Since the dust of sulfide ores is composed of various minerals and elements, the whole effect of depressing dust should be considered while innovating a wetting agent.     

CFD simulation of spontaneous coal combustion in irregular patterns of goaf with multiple points of leaking air

Based on the non-linear air leakage seepage equation for an anisotropic porous medium, on the seepage diffusion equation of multicomponent gas and on the seepage synthetic heat transfer equation of a porous medium, the numerical model for field flow problems of irregular patterns of a goaf with multiple points of leaking air is established and simultaneously solved by the upwind mode finite element method (G3 computer program). According to the complexity of irregular patterns of a goaf with multiple points of leaking air, the flow pattern in a large area of such a goaf and the variation in gases of methane, oxygen and CO and in temperature are theoretically described. In the calculation, the goaf is regarded as a caving anisotropic medium and the coupling effect of methane effusion on spontaneous combustion is considered. The simulation results agree well with practical experience. In addition, the spontaneous combustion process is also simulated, indicating that 1) the spontaneous combustion often takes place near the area where fresh air leaks in and 2) the fire sources can be classified into static and dynamic zones. Therefore, in practical fire preventing and extinguishing, we should clearly distinguish the upstream air leaking points from the downstream ones in order to take proper measures for leakage stopping.     

煤炭自燃标志性气体预测指标的实验研究

设计并研制了氧化热解实验模拟装置，通过对峰峰矿区小屯矿工作面采空区煤样的氧化热解模拟实验，绘制了各氧化热解气体CO2、O2、C2H6和CO等气体浓度随温度的变化曲线，并对其分析找出了该矿采空区煤炭自燃的标志性气体预测指标，从而为掌握工作面采空区煤炭自燃的规律和制定有效合理的煤炭自燃发火的防治措施提供依据，为煤矿的高效生产提供安全保障。     

煤炭自燃标志性气体预测指标的实验研究

设计并研制了氧化热解实验模拟装置,通过对峰峰矿区小屯矿工作面采空区煤样的氧化热解模拟实验,绘制了各氧化热解气体CO2、O2、C2H6和CO等气体浓度随温度的变化曲线,并对其分析找出了该矿采空区煤炭自燃的标志性气体预测指标,从而为掌握工作面采空区煤炭自燃的规律和制定有效合理的煤炭自燃发火的防治措施提供依据,为煤矿的高效生产提供安全保障。     

乌达矿区煤自燃预测标志气体研究

为遴选预测煤自燃进程的标志气体,采集了乌达矿区6个具有代表性的煤样.在实验室开展煤升温氧化气体产物的测定实验,主要测试了煤样在升温氧化条件下各种气体组分的发生量.根据各种气体组分的发生量及最低检测温度,确定了乌达矿区煤自燃预测预报的标志气体,为该矿区煤自燃火灾的预测预报提供了实验依据,对矿区的安全生产具有较好的指导作用.     

自燃煤矸石山爆炸的危害及治理技术

自燃煤矸石山濒发爆炸事故,会造成大量的人员伤亡和经济损失,从而极大地影响煤炭企业的快速发展.结合某矸石山爆炸的实际情况,分析诱发自燃煤矸石山爆炸的主要因素,指出其爆炸所产生高压、高温热浪、粉尘、冲击波等对周围环境的危害,提出自燃煤矸石山爆炸的防治措施,对促使煤炭企业意识到矸石山爆炸的危害并主动预防矸石山爆炸具有重要的现实意义.     

基于热重实验的煤自燃临界氧体积分数分析

对同一种煤样在不同氧体积分数下进行热重实验,利用Matlab得出了该煤样的残留质量比率(TG),质量变化率(DTG),放热速率(DSC)和放热变化率(DDSC)的立体分布和等值线图,研究了不同条件下残留质量和放热速率的变化规律.结果显示,当氧体积分数大于10%时,该煤样在设定的温度内能完全反应和存在最大放热速率,但完全反应对应的温度随着氧体积分数的降低而升高;当氧体积分数小于10%时,尤其是氧体积分数趋向于0时,该煤样难以在设定的温度范围内完全反应,且残留质量随氧体积分数的降低加速上升,同时在实验温度段内放热速率波动不大.最后,对煤样产生不同残留质量的原因进行了分析,结合热重实验得出该煤自燃的临界氧体积分数为18%和8%,从而为采空区自燃"三带"划分提供指导.     

Effects of electrical resistance on the spontaneous combustion tendency of coal and the interaction matrix concept

There have been several developments in determining the spontaneous combustion liability of coal. Most of the methods of concern have purely been based on the internal properties of the coal itself. The relation between the crossing-point method and the electrical resistance of coal was examined here to outline the spontaneous combustion tendency of coal. The electrical resistance property of coal was looked into as a decision-making parameter of the interaction matrix concept for the final decision on the spontaneous combustion tendency.     

激光维持燃烧波对激光-TIG复合热源的影响

激光诱发的等离子体可分为金属蒸汽等离子体和保护气体等离子体。激光-TIG复合焊接过程降低了气体电离条件,促进了激光维持燃烧波(LSC)的形成。通过CCD监测激光-TIC复合热源焊接过程,深入研究了LSC波的形成机理及对激光-TIG复合焊接的影响。     

激光维持燃烧波对激光-TIG复合热源的影响

激光诱发的等离子体可分为金属蒸汽等离子体和保护气体等离子体．激光-TIG复合焊接过程降低了气体电离条件,促进了激光维持燃烧波(LSC)的形成．通过CCD监测激光-TIG复合热源焊接过程,深入研究了LSC波的形成机理及对激光-TIG复合焊接的影响．     

灰色马尔科夫模型对煤自然发火预测的研究

传统灰色模型GM(1,1)对于随机波动性较大的数据序列拟合较差,预测精度较低,为了弥补这一缺陷,更准确预测煤层自然发火的趋势与危险性,将GM(1,1)模型和马尔科夫模型有机结合,构建了灰色马尔科夫模型。用灰色马尔科夫模型对柴里煤矿实测CO发生量进行预测,与传统GM(1,1)模型的预测结果比较,灰色马尔科夫模型的拟合精度更好,平均相对误差更小,简便、实用,能够为矿井煤自燃火灾的防治工作提供科学的理论依据。     

Thermogravimetric study of the effect of a PVA oxygeninsulating barrier on the spontaneous combustion of coal

Coal samples in the air for three months were characterized by Thermogravlmetnc Analysts(TGA).The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined.The moisture loss activation energy,oxidation activation energy and combustion activation energy were calculated by an integral method using the Coats-Redfen formula.The results show that the tendency for spontaneous combustion of three coal samples(judged by the activation energy)falls in the order:CYW>YJL>SW.The oxidation activation energy and combustion activation energy of coal protected by the PVA oxygen-insulating barrier increased.A significant increase in the combustion activation energy was noted,especially for the CYW coal where the increase was 28.53 kJ/mol.Hence,oxidation of the protected coal samples was more difficult.The PVA oxygen-insulating barrier helps to prevent spontaneous combustion of the coal.     

Computer controlled measurement of spontaneous combustion in coal stockpiles of the Western Lignite Corporation, Turkey

1. IntroductionThe event beginning with oxygen absorption of coalfrom air, continuing with oxidation and probably end-ing with a flaming fire is called spontaneous combus-tion. The heat transfer caused by the effect of heattransportation and diffusion mec…     

自燃采空区注氮过程标志性气体分布特征研究

在高瓦斯自燃煤层采空区采取高抽加尾巷排放瓦斯的立体抽放方式时,为避免采空区发生自燃,对采空区进行注N2防火．以华晋焦煤有限责任公司沙曲矿15201工作面为例,在确定采空区自燃三带划分标准的基础上,通过埋管测试方法,研究采空区注N2前后采空区N2和O2分布状态,以及采空区N2运移规律．结果表明,注N2后,注入N2与采空区原有气体混合,气体在采空区漏风压与注N2压力共同作用下运移．N2影响区内O2体积分数下降,氧化带范围缩小,降低了工作面自燃的危险程度．为工作面优化注N2参数和提高注N2防灭火效果提供了参考．     

Rules of variation in hydrogen during reignition of underground fire zones of spontaneous coal combustion

In light of the possibility of reignition when unsealing the closed fire zones, the occurrence of reignition was simulated by a home-made experimental device, hydrogen variety rule from combustion to unsealing was analyzed, the three-stage generation model of hydrogen during reignition in fire zone was put forward and the probability that hydrogen was taken as an indicator gas was discussed. The results show that: when fire zone is ready to unseal, which is filled with hydrogen at a high concentration, it is more prone to reignite.     

综放工作面撤架期间预防采空区遗煤自燃措施探索

煤矿工作面末采撤架期间,由于操作时间长和采空区漏风量较大,因而采空区遗煤很容易发生自燃．鹤煤二矿3407综放工作面在末采撤架期间,通过工作面自燃监测、采空区埋管注浆、预设回撤通道减少回撤时间、阻化剂防灭火以及停采时设置多道密闭、翔闭采空区等措施,确保了工作面末采回撤的安全,同时也得到了较好的经济效益．